docs: def parse_posting_id(text, city):
    """
      Parse the posting ID from the Backpage ad. 
        text -> The ad's HTML (or the a substring containing the "Post ID:" section)
        city -> The Backpage city of the ad
    """
    parts = text.split('Post ID: ')
    if len(parts) == 2:
      post_id = parts[1].split(' ')[0]
      if post_id:
        return post_id + post_id_bp_groups[city]